In FIG. 1, an opposed-piston, opposed-cylinder (OPOC) engine 10 is shown isometrically. An intake piston 12 and an exhaust piston 14 reciprocate within each of first and second cylinders (cylinders not shown to facilitate viewing pistons). Exhaust pistons 14 couple to a journal (not visible) of crankshaft 20 via pushrods 16. Intake pistons 12 couple to two journals (not visible) of crankshaft 20 via pullrods 18, with each intake piston 12 having two pullrods 18.
A portion of an opposed-piston engine 110 is shown in cross section in FIG. 2. An intake piston 112 and an exhaust piston 114 reciprocate in cylinder 116. Pistons 112 and 114 are coupled to journals of crankshaft 120 via a pushrod 122 in the case of piston 114 and via a bridge 124 and two pullrods 126 in the case of piston 112. As engine 110 is an opposed-piston, opposed-cylinder (OPOC) engine, crankshaft 120 is also coupled with a pushrod 132 and pullrod 136 that connect to additional pistons (not shown) in another cylinder (not shown) on the other side of crankshaft 120 from pistons 112 and 114. An example of an OPOC engine is described in more detail in U.S. Pat. No. 6,170,443, which is incorporated herein by reference in its entirety.
In FIG. 3, a schematic representation a cross section taken through the intake ports is shown. A cylinder wall 26 has a plurality of intake ports 24 through which the intake air can be inducted from a plenum 28. Also shown in FIG. 3 are tunnels 30 in which pullrods 32 are disposed. Tunnels 30 restrict the size of plenum 28 in regions 34 thereby restricting flow in those regions. Pullrods 32 can be displaced outwardly from the positions shown in FIG. 3. However, this causes the engine to be wider. An alternative configuration at least partially alleviating such compromise between obtaining the desired flow into the engine and maintaining a compact engine is desired.